Experimental test of the entanglement of radiation generated by the dynamical Casimir effect
Bibliographic record
Abstract
In the dynamical Casimir effect (DCE), a boundary condition for the electromagnetic field is changed rapidly, resulting in generation of pairs of photons [1]. This was experimentally demonstrated in 2011 [2]. Both generation of photons and two-mode squeezing were observed. Quantum theory predicts that the photon pairs are entangled and that the resulting electromagnetic field is in a nonclassical state at zero temperature. Johansson et al. [3] recently suggested how to test entanglement of the DCE radiation by evaluating the log negativity. Here we present such an experimental test. We have measured a sample consisting of an open transmission line terminated by a superconducting quantum interference device (SQUID). The electrical length of the transmission line can be modulated, by changing the magnetic flux through the SQUID loop. Broadband radiation of photon pairs is observed along with strong two mode squeezing. The system is characterized at a temperature of <; 20 mK, and the signal level is calibrated using the SQUID as a shot-noise source. We investigate the cross-correlations for the field at two different frequencies and we recover the covariance matrix. From this matrix we determine the log negativity, which shows weakly positive values indicating that the two modes are entangled. A source of entangled photons can be useful in quantum information applications, for instance to entangle qubits [4].
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".